Many modern-day laser systems require nonlinear optical (NLO) elements. For example, NLO elements are commonly used in applications such as frequency mixing (e.g. harmonic generation, parametric generation/amplification, and the like), Raman amplification, Kerr-lens mode-locking, electro-optic modulation, acousto-optic modulation, and others.
Laser-induced damage (LID) of NLO elements is a major limitation of many modern laser systems. LID occurs as a result of the interaction between laser radiation and the material making up a given NLO element. Accordingly, over time, NLO elements incur LID, which may negatively impact such physical properties as transmittance, reflectivity, refraction indices, and the like. In turn, this degradation of physical properties due to accrued LID eventually leads to failure of NLO elements within a laser system.
LID becomes even more problematic in laser systems that utilize shorter wavelengths of the electromagnetic spectrum, such as deep ultraviolet (DUV) light, with wavelengths less than 300 nm. In addition, laser-induced damage rates are also impacted by material defects present in NLO elements, such as dislocations, impurities, vacancies, and the like. In most cases, material defects in a given NLO element leads to the NLO element being less resistant to LID. Accordingly, the NLO elements have a shorter lifetime as a result of material defects.
The present invention is directed to mitigating the foregoing problems by improving damage resistance of NLO elements utilizing a novel system and method disclosed herein.